The present invention relates to a method and device for assisting a driver of a vehicle during reverse travel, and more particularly, to a method and device in which a distance between a vehicle tail and an obstacle is evaluated during travel of the vehicle in reverse towards the obstacle.
A device of this type is disclosed, for example, in DE 44 04 527 A1, incorporated herein by reference.
It is often necessary to drive vehicles, in particular trucks, trailers or semi-trailers, in reverse, towards an obstacle, for example, when parking or approaching a loading ramp. In such situations, it is generally desirable to achieve as close an approach as possible to the obstacle, without incurring an impact sufficient to cause damage to the vehicle and/or the obstacle. In the case of a truck which travels in reverse towards a loading ramp, it may furthermore be desirable to achieve contact between the loading surface of the truck and the loading ramp, in a manner in which damage to the truck and the loading ramp is effectively avoided.
The known device includes a distance sensor which ascertains the distance between the vehicle tail and an obstacle. In addition, a display device is provided within the driver""s field of vision which displays the distance values determined by the distance sensor. The driver is then able to monitor the displayed distance values during reverse travel towards the obstacle.
In accordance with the known device, the driver decides upon an appropriate speed for approaching the obstacle and determines the correct moment for braking or stopping of the vehicle. An erroneous estimation on the part of the driver in the above decision making process may result in a relatively violent impact of the vehicle against the obstacle, possibly causing damage to the vehicle and/or to the obstacle.
It is therefore the object of the present invention to provide a method and a device which assists the driver of a vehicle during reverse travel, whereby damage to the vehicle and/or to the obstacle can be reliably avoided.
In accordance with these and other objects of the invention, there is provided a method of assisting a driver during reverse travel of a vehicle relative to an obstacle, in which a distance signal representative of a distance between the vehicle tail and the obstacle is evaluated. A speed of the vehicle is then automatically influenced as a function of the evaluated distance signal. A device is also provided for assisting the driver during reverse travel of a vehicle, which includes a distance sensor for emitting a distance signal representative of a distance between the vehicle tail and an obstacle, and an evaluating device for emitting evaluation signals based upon the distance signal received from the distance sensor. A mechanism is also included, in the form of, for example, a vehicle braking system or a vehicle engine control, for influencing a speed of the vehicle in response to the evaluation signals received from the evaluating device, operating in such manner that the speed of the vehicle is influenced automatically as a function of the distance signal.
The invention provides the advantage that the vehicle is automatically brought to a full stop independently of the actions of the driver, either shortly before reaching the obstacle, or upon light contact of the vehicle with the obstacle. The driver is thereby relieved of the responsibility of having to observe and correctly evaluate the distance values indicated on a display device, and is thus better able to concentrate on controlling the other operating parameters of the vehicle. This considerably facilitates operation by the driver during an approach of a vehicle to an obstacle during reverse travel, thus significantly reducing the incidence of damage and the resulting repair costs attendant therewith.
The invention provides the further advantage that safe operation of the vehicle by an inexperienced driver is effected without the requirement of special instructions, since the braking of the vehicle from any operating speed, even an inappropriately high speed of reverse travel, is fully automatic.
In order to determine the vehicle speed, any sensors which may already be present in the vehicle for the sensing of a speed information can be utilized. Thus, for example, signals received from sensors of an anti-lock braking system (ABS) which determine the rotational speeds of individual wheels, or a speed signal of the tachometer, can be used.
In an advantageous further development of the invention, the speed of the vehicle is determined from the change in the distance signal over time, for example, through numerical differentiation. In such manner, the process can also be economically implemented in vehicles not already equipped with speed sensors. When using additional speed signals from speed sensors of the above-mentioned type, a plausibility control of these signals can be carried out by comparison, so that an erroneous triggering of the process according to the invention can be reliably avoided.
In an advantageous embodiment of the invention, a device is provided which, in addition to utilizing a distance sensor and an evaluating device for the signals of the distance sensor, further includes means for influencing the speed of the vehicle. Such influence is implemented, for example, by an electric or electronic control of the vehicle engine and/or of the vehicle braking system. Particularly in connection with a vehicle train consisting of a towing vehicle and trailer or semi-trailer, the means for influencing the speed of the vehicle advantageously additionally comprise a data interface between the towing vehicle and the trailer or semi-trailer for transmission of control data for the drive engine and/or the braking system.
The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements and signals.